In installing underground services, or repairing services already in place, it is quite common to dig a narrow deep trench along the line of the service to the depth at which the service is to be run or to expose the existing service for repair and maintenance. The soil removed from the trench is typically placed on the ground surface immediately adjacent the trench in the area commonly known as the right of way.
After the service has been installed or repaired, the trench is refilled with the soil. However, the compaction of the soil is typically less than the undisturbed ground and the soil will commonly overfill the trench, leaving a mound. In the past, various methods and mechanisms have been used to attempt to compact the soil. Specifically, wheels, drums, plates, both static and vibratory, have been employed. All of these have been used in a multitude of configurations, such as rider, walk behind, hand held and the like, and with varying degrees of success. None of the prior devices address the unique problem of returning all of the spoil to a narrow trench. The soil is also quite prone to subsidence as time passes, often necessitating additional efforts to maintain the proper grade level.
Because of these facts, the task of trenching to permit the installation or repair of utility services and the restoration of the site back to its preexisting condition, specifically soil density and surface condition, is time consuming and costly. Many times, the trenching crew must return to the site to repair subsidence of the surface and other problems that render the site either unsafe or unsightly. The correction of these problems is usually at the contractor's expense.
A need therefore has arisen to develop an apparatus and method whereby the backfilling and compaction of the soil can be done more efficiently and cost effectively. Of specific interest is the ability to compact the soil sufficiently at the time the trench is filled so that subsidence does not occur. Thus, the trencher crew can avoid the costs and difficulty of having to return to a site later.